Subject of the invention is a method and a fastener for closing and sealing pipes ends of pipes subjected to internal pressure, for example plastics pipes subjected to internal pressure tests in suitable apparatus in which a pipe segment is filled with water with a temperature of about 150.degree. C. and subsequently an increased pressure corresponding to required stresses in the pipe wall is established.
A pipe closing and sealing method known so far lies in fixing fasteners consisting usually of four main elements, namely: a cover, a clamping ring, a spring conic ring and an elastic packing, on the pipe ends. Compression of the conic ring on the pipe results from screwing the cover with the clamping ring. At the same time, the cover moving relatively to the clamping ring causes tightening the elastic packing on the pipe.
Such a solution is used by all world firms, e.g. Durapipe from Austria, ITP in the Federal Republic of Germany, Cincinetti from the USA and CEAST from Italy.
The crucial weakness of the presented method and fastener is the long-lasting operation of screwing frequently more than ten screws in each of the fasteners as well as missing relationship between the force compressing the fastener on the pipe and the internal pressure of the medium the pipe is filled with. That leads to occurence of additional stresses in the pipe wall disturbing the test run. For that reason pipe ends are often damaged. Moreover, fasteners are characterized by large overall dimensions and excessive weight.
The aim of the invention is elaborating a new pipe closing and sealing method as well as a fastener serving its realization which will cut significantly the duration of operation of placing and fixing fasteners on a pipe and allow to accomodate the clamp force to the pressure magnitude within the medium filling the pipe.